Analysis of Parallel versus Sequential Splittings for Time-Stepping Physical Parameterizations

Dubal, Mark; Wood, Nigel; Staniforth, Andrew
January 2004
Monthly Weather Review;Jan2004, Vol. 132 Issue 1, p121
Academic Journal
Various numerical issues concerning different approaches to the time stepping of physical parameterizations in numerical weather prediction (NWP) and climate models are examined. Parallel-split and sequential-split methods are explained and analyzed in the context of simple model equations. Terms arising from the use of splitting techniques produce erroneous solutions if the time step is large (of the size typically used in semi-implicit semi-Lagrangian models). Errors in steady-state solutions are examined in particular, as these may lead to systematic biases and climate drift. Splitting methods are then applied to a multiple timescale problem. For large time steps, a useful scheme should produce an accurate discrete representation of the reduced system, which has fast modes removed. Parallel splitting may be of limited use because only explicit versions model reduced systems without splitting errors, but such versions cannot stably integrate fast modes with acceptably large time steps. In a numerical context, sequential-splitting schemes are more flexible. Second-order schemes can be more accurate than first-order ones if the time step is very large, provided careful data initialization is performed to prevent noisy solutions for stiff problems.


Related Articles

  • The Use of Ensembles to Identify Forecasts with Small and Large Uncertainty. Toth, Zoltan; Zhu, Yuejian; Marchok, Timothy // Weather & Forecasting;Aug2001, Vol. 16 Issue 4, p463 

    In the past decade ensemble forecasting has developed into an integral part of numerical weather prediction. Flow-dependent forecast probability distributions can be readily generated from an ensemble, allowing for the identification of forecast cases with high and low uncertainty. The ability...

  • Airstream Boundaries in Numerical Weather Simulations. Cohen, Robert A.; Kreitzberg, Carl W. // Monthly Weather Review;Jan1997, Vol. 125 Issue 1, p1 

    Distinct airstreams, separated by sharp boundaries, are present in numerical weather simulations and can be used to identify characteristic structures in baroclinic storms. To allow objective comparisons between different analyses, a rigorous treatment of airstream boundaries is performed...

  • First International Short-Range Numerical Weather Prediction Workshop on Nonhydrostatic Modeling... Steppeler, J. // Bulletin of the American Meteorological Society;Mar1997, Vol. 78 Issue 3, p469 

    Presents the highlights of the First International Short-Range Numerical Weather Prediction Workshop on Nonhydrostatic Modeling which took place last March 11-13, 1996 in Offenbach, Germany. Purpose of the workshop; Forum on all aspects of atmospheric modeling; Presentation of methods...

  • Representing Drag on Unresolved Terrain as a Distributed Momentum Sink. Wilson, John D. // Journal of the Atmospheric Sciences;5/1/2002, Vol. 59 Issue 9, p1629 

    In numerical weather prediction models, drag on unresolved terrain is usually represented by augmenting the boundary drag on the model atmosphere, in terms of an effective surface roughness length. But as is shown here, if a terrain-following coordinate is defined relative to smoothed terrain,...

  • Does Increasing Horizontal Resolution Produce More Skillful Forecasts? Mass, Clifford F.; Ovens, David; Westrick, Ken; Colle, Brian A. // Bulletin of the American Meteorological Society;Mar2002, Vol. 83 Issue 3, p407 

    This paper examines the impacts of increasing horizontal resolution on the performance of mesoscale numerical weather prediction models. A review of previous studies suggests that decreasing grid spacing to approximately 10 km orless generally produces more realistic mesoscale structures, with...

  • An Adaptive Nonlinear MOS Scheme for Precipitation Forecasts Using Neural Networks. Yuval; Hsieh, William W. // Weather & Forecasting;Apr2003, Vol. 18 Issue 2, p303 

    A novel neural network (NN)–based scheme performs nonlinear model output statistics (MOS) for generating precipitation forecasts from numerical weather prediction (NWP) model output. Data records from the past few weeks are sufficient for establishing an initial MOS connection, which then...

  • CORRIGENDUM. Ebert, Elizabeth E. // Monthly Weather Review;Jun2002, Vol. 130 Issue 6, p1661 

    Presents corrections to the results of a study describing a quantitative precipitation forecasts (QPF) from several numerical weather prediction models. Examination of the usefulness of the QPF of the weather prediction models for estimating the probability of rainfall; Concluding remarks.

  • Scatterometer observations at high wind speeds. Zeng, Lizin; Brown, Robert A. // Journal of Applied Meteorology;Nov98, Vol. 37 Issue 11, p1412 

    Demonstrates the existence of a systematic underestimation of wind speed at high winds int eh buoy and numerical weather prediction winds. Scatterometer winds; Surface wind calibration data; Evaluation of scatterometer winds at high speeds; Possibility of very high wind speeds.

  • Sensitivity of North American Numerical Weather Prediction to Initial State Uncertainty in Selected Upstream Subdomains. Miguel-Macho, Gonzalo; Paegle, Jan // Monthly Weather Review;Aug2001, Vol. 129 Issue 8, p2005 

    Presents a study on the impact of initial uncertainty in localized regions on numerical weather forecast sensitivity over North America. Description of the models, data sets and experiment design; Impact of the initial uncertainty over North America; Discussion of results relative to adaptive...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics